Development of a microcomputer-based system to quantify the effective dose of drug through epithelial cells

It is well documented that the rate-limiting step of pharmaceutical investigation is the amount of drug absorbed through the epithelial cells, not the total dose taken. To date, the only measure of the effective dose of medication is by measuring the circulating level of the ingested medication. This mode of measurement is neither accurate nor practical in determining the active ingredient required. However, a more efficient method of testing which constitutes simplicity and practically is desired. The aim of this project was the design of a microcomputer-based system for detecting and quantifying steroid hormones taken up by mucosal intestinal cells in vitro, for eventual in vivo application in animals and humans. A microcomputer-based system capable of controlling and monitoring four cell membranes simultaneously has been designed, consisting of a microcomputer system and a data acquisition subsystem. The data acquisition subsystem consists of instrumentation amplifiers with an analog-to-digital converter and digital-to-analog converter. This subsystem converts the ionic exchanges first to electrical signals, and then to digital format, to be processed and stored by the microcomputer. Subsequently, the stored information can be clinically interpreted. Due to the complexity of membrane behavior (nonlinear) in response to feedback control signals, software development was difficult. Therefore, a unique scheme was developed to control various unexcitable tissues in order to reach the predetermined values very rapidly, and then to collect cell membrane data periodically.